1. Filed of the Invention
This invention relates to a voltage regulator module (VRM) circuit for a processor and in particular to a VRM circuit having a fault tolerant stand-by voltage regulator module for supplying power to a processor in the event that main VRMs fail. The stand-by VRM is coupled through diodes to the main VRMs.
2. Description of the Related Art
An earlier voltage regulator module for a processor will be explained as follows. The earlier processor converts +12 volts or +5 volts to comply with the processor using a VRM and provides a CPU core voltage and L2 cache voltage.
Processors more advanced than INTEL Pentium II microprocessors need two VR because the processor core voltage level and L2 cache voltage level are different. When the voltage regulator modules supplying voltages supply a low voltage or become inoperative because of the high consumption power of the microprocessor, the processor also fails or becomes inoperative.
Afterward, because the processor has no back-up devices, the system is down if the processor is a single microprocessor and the system performance is reduced, if a multi-processor system.
Also, a microprocessor more advanced than INTEL Pentium II microprocessors need two voltage regulator modules per processor, so that the multi-processor system depends on many voltage regulator modules and is increased in a dependence of voltage regulator module.
The following patents each discloses features in common with the present invention but dot not teach or suggest the specifically recited fault tolerant voltage regulator module circuit of the present invention: U.S. Pat. No. 5,745,670 to Linde, entitled Fault Tolerant Power Supply System, U.S. Pat. No. 5,598,041 to Willis, entitled Efficient Fault Tolerant Switching Circuit For Redundant D.C. Power Supplies, U.S. Pat. No. 5,811,895 to Suzuki et al., entitled Power Supply Circuit For Use With A Battery And An AC Power Adaptor, U.S. Pat. No. 5,493,155 to Okamoto et al., entitled Electric Power Supply System, U.S. Pat. No. 5,498,913 to Moritani, entitled Power Supply Control Apparatus With A Manually Operable Control Switch, U.S. Pat. No. 4,954,993 to Yamaguchi et al., entitled Semiconductor Integrated Circuit Having A Plurality Of Circuit Blocks Respectively Supplied With Power From Different Power Sources, U.S. Pat. No. 5,103,157 to Wright, entitled Common Emitter Amplifiers Operating From A Multiplicity Of Power Supplies, U.S. Pat. No. 5,138,184 to Keefe, entitled Solid State Static Power Transfer Mechanism, U.S. Pat. No. 5,187,382 to Kondo, entitled Apparatus For Detecting The Existence Of An Abnormality In A Vehicle Operator Protection System, U.S. Pat. No. 4,791,443 to Foley et al., entitled Photographic Processor With Auxiliary Power Supply, U.S. Pat. No. 4,812,672 to Cowan et al, entitled Selective Connection OfPower Supplies, U.S. Pat. No. 5,708,771 to Brant et al., entitled Fault Tolerant Controller System And Method, and U.S. Pat. No. 5,796,274 to Willis et al., entitled Fault Tolerant Most Driver.